Patent GB-956190-A (GB)
Title: Improvements relating to braking installations for vehicles
IPC: B60T13/14
Filed: 1962-05-03
Abstract: 956,190. Fluid-pressure brakes. DAIMLERBENZ A.G. May 3, 1962 [May 12, 1961], No. 17075/62. Heading F2F. A brake installation for a vehicle comprises first and second wheel-brake systems, the first system comprising a reservoir and a brake valve for controlling the pressure in the system and the second system having its pressure controlled by a master cylinder, the master cylinder and the brake valve being disposed at opposite ends of a balance beam acted on by a brake pedal or other operating member, and a pressure-limiting valve being provided in the duct, leading to the brake cylinders of the rear wheels, of one system. As shown, each wheel is provided with two brake cylinders, i.e. 18, 19, for the front wheels and 20, 21 for the rear wheels. Cylinders 19 are operated directly from a brake valve 36 to which hydraulic fluid is supplied by a reservoir 25 at a pressure determined by a relief valve 24 of a pump 22. Air is compressed in a chamber 27 of the reservoir to maintain the hydraulic pressure should the pump temporarily stop, a non-return valve 31<SP>1</SP> being interposed between the reservoir and the pump and a further similar reservoir 3111 smoothing the flow from the pump. Brake valve 36 is operated through a rod 35 from one end of a balance beam 34 acted on by foot pedal 32. The other end of the balance beam acts on the operating rod 37 of a master cylinder 38 which supplies fluid via conduit 44 to the rear wheel cylinders 20. Front wheel cylinders 18 are supplied with fluid from a reservoir 26, similar to the reservoir 25, through a cut-in valve 45 controlled by the pressure in the conduit 44, a non-return valve 31 being interposed between the reservoir 26 and the pump 22. Rear wheel cylinders 21 are supplied with fluid by the valve 36 through a pressurelimiting valve 48 the limiting pressure of which is determined by the pressure in rear wheel fluid springs 15. The valve 48 is also made responsive to the pressure in reservoir 26 to cut-off the supply of fluid to cylinders 21 should this pressure fall below a predetermined value. The master cylinder 38, brake valve 36, non-return valves 31, 31<SP>1</SP> and valves 45, 48 are incorporated in a single block (Fig. 2) to which the reservoirs 25, 26 are attached as shown. The brake valve 36 consists of a hollow plunger 52, the interior of which normally connects the outlet conduit 40 to exhaust via a valve 50 which is closed when rod 35 is moved by an operating force, further movement compressing spring 54 to admit fluid from an inlet 53. The cut-in valve 45 is a ball valve 67 opened to supply fluid to outlet 47 by a plunger 66 carried by a piston 65 acted on at opposite sides by outlet pressure and master cylinder pressure. The limiting valve 48 consists of a similar ball valve 60 acted on by plunger 61 carried by differential piston 69, 70 which is acted on by outlet pressure on its smaller face and by suspension fluid pressure on its larger face. This ball valve, however, seats in a slidable member 56 which is held against a shoulder by the pressure in reservoir 26 but slides away from the shoulder to close the valve whenever the pressure in reservoir 26 falls below a predetermined value.